So you have found yourself a cool car that needs some love, being it a barn find, someone else's abandoned project, or just a car that has been neglected for years. It's a fifth of the cost of the same car in "ready-to-go" form, and you figure that you are willing to wait to drive it if it means you can pay for it bit by bit, as you decide how to have it built to suit your liking. It's like making payments on it, and the best part is you get to decide when and how much money to put into it. Sounds great, right?
What ends up happening is that there is always something else more pressing when it comes to disposable money and your "project" will linger and progress extremely slowly. On top of it you'll get a lot of calls from your mechanic that will sound like this "Oh hey, we were removing the rear suspension to install those new springs you sent us, but the frame is rotted under there so it has to go to get repaired and welded first..."... It is a frustrating process that often doesn't see the end of the tunnel; hence all the "unfinished project for sale" ads you see where someone is trying to unload their "problem" as the wife has decided it's time to reclaim her garage. I have personally seen project cars that had changed multiple owners without making any progress in between hands.
Even when people have a number of restorations under their belt, and have "the right guy" for the job, it will be at least a couple of years before you get to drive the car, often more: the right guy has a line outside the door of people that want his work. Don't be fooled by TV shows where they go from a banged up rust bucket to a glorious build in 3 weeks. That's TV, where money is no object, and their builds make no financial sense.
So my suggestion is: buy the best car you can afford that's ready to go with minimal work. Meaning that no car of this kind will need nothing (you will at least have a mechanic check that your brakes work...), but it should take a couple of weeks at the most. After that, you're ready to go drive and enjoy your car, knowing how much you spent upfront, ready to make memories while driving by some poor guy that has a frame sitting outside his garage while he tries to figure out how to fit all those boxes of parts that came with it...
So what to do when you "must" have a car built? There are several cases in which this is the only possible way: you have a car that has sentimental value, so it has to be that one you drive. Or sometimes you want a car that is simply not available in the used market (from either scarcity or because the price for the few ones for sale is just too steep). In that case, unless you possess the time, skills, money and room to do it yourself: let a professional do it for you.
These are people that have followed the process of a build many times before, they have the resources to get it done right, quick(er...) and cost efficiently. They also have the time to devote to it: you pay them to hound down the parts, to follow up with the body-shop and to oversee the project as a whole. They are also well versed in understanding what you want from the car, and how to achieve it. They can steer you away from costly mistakes and ensuring that you get exactly what you want.
If you read all this and you find yourself agreeing, feel free to reach out to me to see how I can help you get driving: from a simple inspection to quoting you a full build, I'm your guy.